The present invention relates to a banking technique in civil engineering and construction fields, and more particularly, a banking structure using rocks producing acid drainage as backing materials.
Sulfide minerals may be minerals that are commonly produced from rocks and sediments. The sulfide minerals may be produced by various geological processes such as diagenesis of sediments deposited under reducing environments, deposition from hot water, and reaction between hot water and rocks. Sulfide minerals may be produced from various kinds of rocks according to generation environments. Iron pyrites may be the most representative sulfide minerals.
In case of the iron pyrites, the iron pyrites may be stabilized if they exist in the underground or under a water surface in a state where they are blocked from the atmosphere. However, if the iron pyrites are exposed to the surface of the earth by underground excavation, drainage, dredge, and the like, the iron pyrites meet oxygen and thus are oxidized to produce acid drainage.
The drainage produced by the oxidation of the sulfide minerals may have acidity. Thus, the drainage may contain a large amount of Fe and heavy metals that are eluted from the sulfide minerals. Also, since the drainage generated by the oxidation of the sulfide minerals dissolves aluminum silicate minerals, the drainage may contain a large amount of Al that is eluted from the aluminum silicate minerals.
In recent years, large scale underground excavation frequently occurs due to road building and residential land and industrial complex development. Rocks containing the sulfide minerals exposed to the surface of the earth during the underground excavation may produce the acid drainage to cause various problems such as environmental pollution, corrosion of structures, vegetation withering, scenery damage, rock weathering promotion, reduction of ground stability, and the like. Thus, adequate processing and recycle of the rocks containing the sulfide minerals produced from the large scale underground excavation sits are coming to the fore as pending issues in construction sites.
Typically, the sulfide mineral rocks may be buried for processing. Here, when the sulfide mineral rocks are buried, a collecting well, a perforated drainpipe, a pond, and a waterproof sheet, which process percolating water, are applied to minimize effects that have an influence on environments. However, the construction method may be complicated, and a relatively large amount of cost and time may be required. Also, the perforated drainpipe and waterproof sheet may be frequently damaged when constructed and thus deteriorated in effectiveness.
Also, due to leakage of aggregate, needs for recycling the excavated rocks into banking materials are increasing. Thus, although there is an attempt to recycle the rocks into the banking materials, a technique for solving problem of all sorts due to the oxidation of the sulfide minerals within the rocks through penetration of rainwater and the contact with air has not been proposed. Thus, the industrial recycling of the rocks is investigated only negative attention.